HDU 1247 Trie树

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题意：按字典序输入一系列单词，输入结束后，判断哪些单词是由其余两个单词连接而成。若是，则输出（输出也按字典序）。

#include <iostream>using namespace std;char list[50001][26];const int kind = 26;int cnt = 0;struct Treenode{bool flag;Treenode *next[kind];Treenode(){flag = false;for ( int i = 0; i < kind; ++i )next[i] = NULL;}} node[100000];void Insert ( Treenode *&root, char *word ){Treenode *location = root;if ( location == NULL ){location = &node[cnt++];root = location;}int id, i = 0;while ( word[i] ){id = word[i] - 'a';if ( location->next[id] == NULL )location->next[id] = &node[cnt++];location = location->next[id];++i;}location->flag = true; /*注意标记单词的最后一个字母，说明在这之前的字母组成一个单词，以便查询时划分*/}bool check ( Treenode *root, char* word ){Treenode *location = root;if ( location == NULL ) return false;int id, i = 0, len = strlen(word);while ( word[i] ){id = word[i] - 'a';if ( location->next[id] == NULL )return false;if ( i == len-1 && location->next[id]->flag == true )return true;/*查找到最后一个字符时，节点的标记应该是true,这样才是完全匹配的*/location = location->next[id];++i;}return false;}bool Search ( Treenode *root, char * word ){Treenode *location = root;if ( location == NULL ) return false;int id, i = 0, len = strlen(word);while ( word[i] ){id = word[i] - 'a';if ( location->next[id] == NULL )return false;if ( location->next[id]->flag == true )/*当检测到一个标记时说明单词的前半部分已经检测到，现在只需检测后面一部分是否能由另一个单词构成*/{if ( i + 1 < len && check(root,&word[i+1]) )return true;}location = location->next[id];++i;}return false;}int main(){int i = 0, j;Treenode *root = NULL;while ( scanf("%s", list[i]) != EOF ){Insert(root,list[i]);++i;}for ( j = 0; j < i; ++j ){if ( Search(root,list[j]) )printf("%s\n",list[j]);}return 0;}